The present disclosure provides an approach for producing colored toner compositions and, in embodiments, to a system and method for predicting color properties of toner compositions.
In today's business and scientific world, color has become essential as a component of communication. Color facilitates the sharing of knowledge and ideas. Companies involved in the development of digital color print engines are continuously looking for ways to improve the image quality of their products. One of the elements that affects image quality is the ability to consistently produce the same image on a printer from one day to another, from one week to the next, month after month. Users have become accustomed to printers and copiers that produce high quality color and gray-scaled output. Users now expect to be able to reproduce a color image with consistent quality on any compatible printing device, including another device within an organization, a device at home, or a device used anywhere else in the world.
Color images are commonly represented as one or more separations, each separation comprising a set of color density signals for a single primary or secondary color. Color density signals are commonly represented as digital gray or contone pixels, varying in magnitude from a minimum to a maximum, with a number of gradients corresponding to the bit density of the system. Thus, a common 8-bit system provides 256 shades of each primary color. A color can therefore be considered the combination of magnitudes of each pixel, which when viewed together, present the combination color.
CMYK is a color model in which all colors are described as a mixture of four process colors (i.e., cyan, magenta, yellow, and black). CMYK is the standard color model used in offset printing for full-color documents. Because such printing uses inks of these four basic colors, it is often called four-color printing and is a subtractive color model. The CMYK model works by partially or entirely masking certain colors on the typically white background (that is, absorbing particular wavelengths of light). Such a model is called subtractive because inks “subtract” brightness from white. In additive color models such as RGB (i.e., red, green, blue), white is the “additive” combination of all primary colored lights, while black is the absence of light. In the CMYK model, it is just the opposite. In other words, white is the natural color of the paper or other background, while black results from a full combination of colored inks. To save money on ink, and to produce deeper black tones, unsaturated and dark colors are produced by substituting black ink for the combination of cyan, magenta and yellow.
There are different ways of representing color. One way color is described consists of the following parameters: hue, lightness and saturation. Hue represents the actual color wavelength (red, blue, etc.); lightness corresponds to the white content; while saturation captures the richness or amplitude in color. Another way of describing color uses the three dominant primary colors red, blue and green (RGB). By combining these primary colors, in different intensities, most colors visible to humans can be reproduced. Monitors and scanners use the additive RGB color process. Printers use the subtractive CMYK color process based on light reflected from inks coated on a substrate. The color representations described above fail to reproduce color predictably because they are observer or device dependent.
Moreover, while the CMYK color space is the standard color space used by production printers, the Red-Green-Blue (RGB) color space is a personal computer's native color space. As a result, display devices generally use a different color model, namely the RGB model. One of the most difficult aspects of desktop publishing in color is color matching, which is properly converting the RGB colors into CMYK colors so that what gets printed looks the same as what appears on the monitor.
Both RGB and CMYK color spaces are device-dependent color spaces; i.e., the colors rendered depend on the device that produces the colors. For example, the colorimetric attributes produced by a scanner vary from the colorimetric attributes visible on a monitor since a scanner uses a CCD (charge coupled device) array to capture colors, while a monitor produces colors from light-emitting phosphors. Additionally, the process of converting an image from the RGB color space to the CMYK color space generally compresses the colors into a smaller range.
Improved methods for producing colored toners, including systems that are not device-dependent, remain desirable.